Modeling of biofilm growth and the related changes in hydraulic properties of porous media

Pore blocking is considered to dominate the hydraulic conductivity in solute transport processes. Biomass accumulation is effective in reducing the hydraulic conductivity of porous medium. In this paper, the sphere model and the cut-and-random-rejoin-type model were adopted to establish mathematical equations for hydraulic characteristics of porous media caused by biological clogging. A new mathematical correlation was proposed to address the coupling effect of hydraulic, biofilm growth fields on the basis of thorough review on Kozeny-Carman equation relevant researches. The time-dependent solution were investigated with the consideration of a series of different model factors. The study found that there are similar phenomena both in the sphere model and in the cut-and-random-rejoin-type model. When the pores of the porous media are filled with biofilms, the pore volume is continuously reduced, and the porosity of the porous media continues to decrease. Macroscopically, it is manifested as a decrease in permeability. The model image analysis shows that growth of biofilm in a porous medium reduces the total volume and the average size of the pores and directly affects the permeability of pores. But this effect is not permanent, the pores will not be completely blocked, and the permeability will not drop to zero.